The Multiple-input multiple-output (MIMO) technique combined with non-orthogonal multiple access (NOMA) has been considered to enhance total system performance. This paper studies the bit error rate of two-user power-domain NOMA systems using successive interference cancellation receivers, with zeroforcing equalization over quasi-static Rayleigh fading channels. Successive interference cancellation technique at NOMA receivers has been the popular research topic due to its simple implementation, despite its vulnerability to error propagation. Closed-form expressions are derived for downlink NOMA in single-input single-output and uncorrelated quasi-static MIMO Rayleigh fading channel. Analytical results are consolidated with Monte Carlo simulation.
A Low Power High Bandwidth Four Quadrant Analog Multiplier in 32 NM CNFET Tec...VLSICS Design
Carbon Nanotube Field Effect Transistor (CNFET) is a promising new technology that overcomes several limitations of traditional silicon integrated circuit technology. In recent years, the potential of CNFET for analog circuit applications has been explored. This paper proposes a novel four quadrant analog multiplier design using CNFETs. The simulation based on 32nm CNFET technology shows that the proposed multiplier has very low harmonic distortion (<0.45%), large input range (±400mV), large bandwidth (~50GHz) and low power consumption (~247µW), while operating at a supply voltage of ±0.9V.
Bit Error Rate Performance of MIMO Spatial Multiplexing with MPSK Modulation ...ijsrd.com
Wireless communication is one of the most effective areas of technology development of our time. Wireless communications today covers a very wide array of applications. In this, we study the performance of general MIMO system, the general V-BLAST architecture with MPSK Modulation in Rayleigh fading channels. Based on bit error rate, we show the performance of the 2x2 schemes with MPSK Modulation in noisy environment. We also show the bit error rate performance of 2x2, 3x3, 4x4 systems with BPSK modulation. We see that the bit error rate performance of 2x2 systems with QPSK modulation gives us the best performance among other schemes analysed here.
This document summarizes a new complexity reduction method for V-BLAST MIMO systems in communication channels. It proposes two methods: 1) a low complexity QR algorithm and 2) a consecutive iterations reduction method. These methods are compared to traditional detection methods like zero forcing (ZF), minimum mean square error (MMSE), successive interference cancellation (SIC), and maximum likelihood (ML). Simulation results show that the proposed algorithms not only reduce computational complexity but also achieve significantly better bit error rate and probability of error performance compared to traditional V-BLAST techniques. The document analyzes the performance of different equalizers using the V-BLAST algorithm and evaluates the proposed methods versus traditional approaches.
Performance Analysis of Various Symbol Detection Techniques in Wireless MIMO ...IOSR Journals
Wireless communication is one of the most effective areas of technology development of our time.
Wireless communications today covers a very wide array of applications. In this paper, we study the
performance of general MIMO system, the performance of Zero Forcing (ZF), Linear Least Square Estimator
(LLSE), V-BLAST/ZF, V-BLAST/LLSE of 4x4, 4x6 & 4x8 with 4-QAM & 16-QAM modulation in i i d Rayleigh
fading channel. We seen that SER performance of 4x8 antennas and 4-QAM modulation scheme outperforms
others. Result shows that for higher modulation schemes SER performance degrades as well as SER
performance increases for higher no of receiver antennas
At this present scenario, the demand of the system capacity is very high in wireless network. MIMO
technology is used from the last decade to provide this requirement for wireless network antenna
technology. MIMO channels are mostly used for advanced antenna array technology. But it is most
important to control the error rate with enhanced system capacity in MIMO for present-day progressive
wireless communication. This paper explores the frame error rate with respect to different path gain of
MIMO channel. This work has been done in different fading scenario and produces a comparative analysis
of MIMO on the basis of those fading models in various conditions. Here, it is to be considered that
modulation technique as QPSK to observe these comparative evaluations for different Doppler frequencies.
From the comparative analysis, minimum amount of frame error rate is viewed for Rician distribution at
LOS path Doppler shift of 0 Hz. At last, this work is concluded with a comparative bit error rate study on
the basis of singular parameters at different SNR levels to produce the system performance for uncoded
QPSK modulation.
This document discusses a vector precoding scheme for multi-user MIMO systems. It proposes using vector precoding to circumvent the channel inversion required for zero forcing precoding. The scheme develops a joint transmitter-receiver design where the transmitter precoder lies in the null space of other users' channels to eliminate multi-user interference. Simulation results show the proposed approach improves bit error rate performance by an order of magnitude compared to zero forcing, and increases MIMO broadcast channel capacity with lower complexity than inversion-based techniques.
Study on transmission over Nakagami-m fading channel for multiple access sche...TELKOMNIKA JOURNAL
In this paper, a downlink performance in non-orthogonal multiple access (NOMA) system is considered. With regard to different priority for two NOMA users, we exploit the closed-form expressions of outage probability over wireless fading channel following Nakagami-m fading. The fixed power allocation factor scheme is examined to reduce the complexity in computation regarding performance analysis. In our analysis, perfect successive interference cancellation (SIC) is applied in order to achieve perfect signal decoding operation. Simulation results show that the considered NOMA downlink scheme is affected by transmit SNR, power allocation factors, fading parameters.
IMPROVEMENT OF LTE DOWNLINK SYSTEM PERFORMANCES USING THE LAGRANGE POLYNOMIAL...IJCNCJournal
The document describes research on improving the performance of LTE downlink systems using Lagrange polynomial interpolation for channel estimation. It presents the MIMO-OFDM transmission scheme used in LTE and discusses various channel estimation techniques including linear, sinus cardinal, Newton polynomial, and Lagrange polynomial interpolation. Simulation results show that Lagrange polynomial interpolation outperforms other methods in terms of block error rate, throughput, and error vector magnitude versus signal-to-noise ratio. The optimal order of the Lagrange polynomial is determined by evaluating performance for different orders.
A Low Power High Bandwidth Four Quadrant Analog Multiplier in 32 NM CNFET Tec...VLSICS Design
Carbon Nanotube Field Effect Transistor (CNFET) is a promising new technology that overcomes several limitations of traditional silicon integrated circuit technology. In recent years, the potential of CNFET for analog circuit applications has been explored. This paper proposes a novel four quadrant analog multiplier design using CNFETs. The simulation based on 32nm CNFET technology shows that the proposed multiplier has very low harmonic distortion (<0.45%), large input range (±400mV), large bandwidth (~50GHz) and low power consumption (~247µW), while operating at a supply voltage of ±0.9V.
Bit Error Rate Performance of MIMO Spatial Multiplexing with MPSK Modulation ...ijsrd.com
Wireless communication is one of the most effective areas of technology development of our time. Wireless communications today covers a very wide array of applications. In this, we study the performance of general MIMO system, the general V-BLAST architecture with MPSK Modulation in Rayleigh fading channels. Based on bit error rate, we show the performance of the 2x2 schemes with MPSK Modulation in noisy environment. We also show the bit error rate performance of 2x2, 3x3, 4x4 systems with BPSK modulation. We see that the bit error rate performance of 2x2 systems with QPSK modulation gives us the best performance among other schemes analysed here.
This document summarizes a new complexity reduction method for V-BLAST MIMO systems in communication channels. It proposes two methods: 1) a low complexity QR algorithm and 2) a consecutive iterations reduction method. These methods are compared to traditional detection methods like zero forcing (ZF), minimum mean square error (MMSE), successive interference cancellation (SIC), and maximum likelihood (ML). Simulation results show that the proposed algorithms not only reduce computational complexity but also achieve significantly better bit error rate and probability of error performance compared to traditional V-BLAST techniques. The document analyzes the performance of different equalizers using the V-BLAST algorithm and evaluates the proposed methods versus traditional approaches.
Performance Analysis of Various Symbol Detection Techniques in Wireless MIMO ...IOSR Journals
Wireless communication is one of the most effective areas of technology development of our time.
Wireless communications today covers a very wide array of applications. In this paper, we study the
performance of general MIMO system, the performance of Zero Forcing (ZF), Linear Least Square Estimator
(LLSE), V-BLAST/ZF, V-BLAST/LLSE of 4x4, 4x6 & 4x8 with 4-QAM & 16-QAM modulation in i i d Rayleigh
fading channel. We seen that SER performance of 4x8 antennas and 4-QAM modulation scheme outperforms
others. Result shows that for higher modulation schemes SER performance degrades as well as SER
performance increases for higher no of receiver antennas
At this present scenario, the demand of the system capacity is very high in wireless network. MIMO
technology is used from the last decade to provide this requirement for wireless network antenna
technology. MIMO channels are mostly used for advanced antenna array technology. But it is most
important to control the error rate with enhanced system capacity in MIMO for present-day progressive
wireless communication. This paper explores the frame error rate with respect to different path gain of
MIMO channel. This work has been done in different fading scenario and produces a comparative analysis
of MIMO on the basis of those fading models in various conditions. Here, it is to be considered that
modulation technique as QPSK to observe these comparative evaluations for different Doppler frequencies.
From the comparative analysis, minimum amount of frame error rate is viewed for Rician distribution at
LOS path Doppler shift of 0 Hz. At last, this work is concluded with a comparative bit error rate study on
the basis of singular parameters at different SNR levels to produce the system performance for uncoded
QPSK modulation.
This document discusses a vector precoding scheme for multi-user MIMO systems. It proposes using vector precoding to circumvent the channel inversion required for zero forcing precoding. The scheme develops a joint transmitter-receiver design where the transmitter precoder lies in the null space of other users' channels to eliminate multi-user interference. Simulation results show the proposed approach improves bit error rate performance by an order of magnitude compared to zero forcing, and increases MIMO broadcast channel capacity with lower complexity than inversion-based techniques.
Study on transmission over Nakagami-m fading channel for multiple access sche...TELKOMNIKA JOURNAL
In this paper, a downlink performance in non-orthogonal multiple access (NOMA) system is considered. With regard to different priority for two NOMA users, we exploit the closed-form expressions of outage probability over wireless fading channel following Nakagami-m fading. The fixed power allocation factor scheme is examined to reduce the complexity in computation regarding performance analysis. In our analysis, perfect successive interference cancellation (SIC) is applied in order to achieve perfect signal decoding operation. Simulation results show that the considered NOMA downlink scheme is affected by transmit SNR, power allocation factors, fading parameters.
IMPROVEMENT OF LTE DOWNLINK SYSTEM PERFORMANCES USING THE LAGRANGE POLYNOMIAL...IJCNCJournal
The document describes research on improving the performance of LTE downlink systems using Lagrange polynomial interpolation for channel estimation. It presents the MIMO-OFDM transmission scheme used in LTE and discusses various channel estimation techniques including linear, sinus cardinal, Newton polynomial, and Lagrange polynomial interpolation. Simulation results show that Lagrange polynomial interpolation outperforms other methods in terms of block error rate, throughput, and error vector magnitude versus signal-to-noise ratio. The optimal order of the Lagrange polynomial is determined by evaluating performance for different orders.
This document analyzes the effects of carrier frequency offset (CFO) and fading branch correlation (FBC) on the performance of an asynchronous multi-carrier coded-division multiple-access (MC-CDMA) system. It establishes models for an MC-CDMA system with transmitter and receiver, and examines how CFO and FBC impact the bit error rate (BER) performance. Equations are derived relating CFO and FBC, and simulation results are presented showing which parameter, CFO or FBC, has a greater influence on system performance.
Full-duplex user-centric communication using non-orthogonal multiple accessTELKOMNIKA JOURNAL
This paper proposes an improved user-centric Non-Orthogonal Multiple Access (NOMA) communication in two-base station networks with in-band full duplex (IBFD) user. We derive the achievable rates of the proposed user-centric NOMA systems. For benchmarking purposes, we also derive the achievable rate for the user-centric system deploying conventional NOMA schemes, Orthogonal Multiple Access (OMA) schemes and point-point communication systems. We then analyze and simulate the performance of the proposed and all the benchmarked systems. We found that our proposed user-centric NOMA approach has a 64% improvement in the total achievable rate when compared to the benchmarked approach under similar power constraint.
With the rise of data-intensive mobile applications, network operators must find ways to increase network capacity to meet demand. MIMO (Multiple-Input Multiple-Output) techniques, which use multiple antennas at the transmission and reception ends, have the potential to significantly boost network throughput through spatial multiplexing. However, optimizing networks for MIMO's full benefits presents challenges, as MIMO works best under rich scattering conditions and requires accurate measurement of multipath environments. Real-world RF measurements tailored for MIMO networks can help operators overcome these challenges and maximize throughput gains from MIMO without additional spectrum or infrastructure.
Combining SFBC_OFDM Systems with SVD Assisted Multiuser Transmitter and Multi...IOSR Journals
Abstract: In this work, we exploit the SVD assisted multiuser transmitter (MUT) and multiuser detector (MUD) technique, using downlink (DL) preprocessing transmitter and DL postprocessing receiver matrice .In combination with space frequency block coding (SFBC). And also propose the precoded DL transmission scheme, were the both proposed schemes take advantage of the channel state information (CSI) of all users at the base station (BS), but only of the mobile station (MS)’s own CSI, to decompose the MU MIMO channels into parallel single input single output (SISO), these two proposed schemes are compared to the vertical layered space time (V_BLAST) combined with SFBC (SFBC_VBLAST). Our Simulation results show that the performance of the proposed scheme with DL Zero Forcing (ZF) transmitter for interference canceller outperforms the SFBC_VBLAST and the precoded DL schemes with ZF receiver in frequency selective fading channels. Keywords – Post processing, Preprocessing,, SFBC, SVD, ZF.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Iaetsd stbc-ofdm downlink baseband receiver for mobile wmanIaetsd Iaetsd
This document discusses a proposed space time block code-orthogonal frequency division multiplexing (STBC-OFDM) downlink baseband receiver for mobile wireless metropolitan area networks (WMANs). The proposed receiver applies STBC-OFDM techniques using two transmit antennas and one receive antenna to provide robust performance in outdoor mobile environments. It includes a simple and robust synchronizer and an accurate but affordable channel estimator to overcome challenges of multipath fading channels. Simulation results show the receiver can achieve a coded bit error rate of less than 10-6 for 16QAM modulation under vehicle speeds of 120 km/hr while supporting up to 27.32 Mb/s of uncoded data transmission. The receiver designed in a 90-nm CMOS
This document summarizes research on multi-numerology 5G new radio (NR) systems. It begins with an introduction comparing the flexibility of NR and LTE, noting that NR allows simultaneous use of multiple numerologies. Section II further describes differences in flexibility between NR and LTE regarding 3GPP standards. Section III then outlines potential research opportunities for improving multi-numerology systems, such as addressing interference between non-orthogonal numerologies. Finally, Section IV indicates that simulation results on inter-numerology interference will be presented as a function of guard allocation and parameters.
Computationally Efficient Multi-Antenna Techniques for Multi-User Two-Way Wire...IJECEIAES
In this work, we are interested in implementing, developing and evaluating multi-antenna techniques used for multi-user two-way wireless relay networks that provide a good tradeoff between the computational complexity and performance in terms of symbol error rate and achievable data rate. In particular, a variety of newly multi-antenna techniques is proposed and studied. Some techniques based on orthogonal projection enjoy low computational complexity. However, the performance penalty associated with them is high. Other techniques based on maximum likelihood strategy enjoy high performance, however, they suffer from very high computational complexity. The Other techniques based on randomization strategy provide a good trade-off between the computational complexity and performance where they enjoy low computational complexity with almost the same performance as compared to the techniques based on maximum likelihood strategy.
OFDM is a digital multi-carrier modulation technique that divides the available spectrum into multiple orthogonal subcarriers. It allows high spectral efficiency by spacing the carriers to maintain orthogonality even when their spectra overlap. The document provides an intuitive explanation of OFDM using analogies like a shower head vs faucet and multiple smaller trucks vs one large truck. It explains how OFDM provides resistance to interference by spreading data across orthogonal subcarriers rather than a single carrier. The key concept of orthogonality allows the subcarriers to overlap without interference by ensuring the area under one subcarrier's frequency multiplied by another is always zero.
This document summarizes a research paper on developing a reconfigurable hardware architecture for implementing maximum likelihood (ML) decoding algorithms in MIMO systems. It begins by introducing MIMO techniques for improving wireless communication throughput. It then describes various MIMO receiver algorithms and chooses ML for its best performance. The document outlines the ML decoding algorithm and presents a Simulink model. It discusses implementing the MIMO decoder as a modular, reconfigurable architecture on an FPGA and shows placement results on a Xilinx Virtex 4 chip. The work aims to provide flexible hardware for MIMO signal processing applications.
1. The document proposes a scheme called Superimposed Spatial Modulation (SSM) that allows for doubling of information conveyed in the spatial position of transmitting antennas.
2. SSM superimposes two independent spatial modulation systems on the same antenna array. Each system transmits different components of orthogonal symbols.
3. This approach increases spectral efficiency over conventional spatial modulation by doubling the size of the possible antenna constellations.
An Efficient Performance of Mimo - Ofdm Based Cognitieve Radio System for Arr...IOSR Journals
Abstract: The wireless channel is central within this context, thus estimating the channel is the key to make CR operational, taking in consideration that the transmission-reception technology is available. In this thesis, we design a MIMO system using OFDM modulation technology to transmit and receive two signals over the mobile wireless channel. First formulate the pilot design as a new optimization problem. We use MIMO concept to enhance system capacity and robustness of the wireless transmission. In Multi-Input Multi-Output (MIMO) based cognitive radio (CR) systems, with the increasing demand for data rate and reliability in Wireless communicationsand devices, several issues become very important like bandwidth efficiency, quality of service and radio coverage. In this new scheme, adaptive arrays are group-selected in the spatial domain. Simulation shows that the proposed system can get significant performance improvements over the conventional array based OFDM systems over frequency-selective multipath fading channels with cognitive radio (CR) system. Keywords: Cognitive radios, MIMO, OFDM, and Joint transmit and receive group selected arrays.
Classical Discrete-Time Fourier TransformBased Channel Estimation for MIMO-OF...IJCSEA Journal
In this document, we look at various time domain channel estimation methods with this constraint of null carriers at spectrumborders.We showin detail howto gauge the importance of the “border effect” depending on the number of null carriers, which may vary from one system to another. Thereby we assess the limit of the technique discussed when the number of null carriers is large. Finally the DFT with the truncated singular value decomposition (SVD) technique is proposed to completely eliminate the impact of the null subcarriers whatever their number. A technique for the determination of the truncation threshold for any MIMO-OFDM system is also proposed.
A Potent MIMO–OFDM System Designed for Optimum BER and its Performance Anal...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Performance of the MIMO-MC-CDMA System with MMSE EqualizationTamilarasan N
Multipath fading and spectral crowding are the
major challenges in dealing higher data rate in future
broadband wireless communication system. Multi-carrier
Modulation like Multicarrier code division multiple access
(MC-CDMA) can tackle the problem and provide higher data
rate for future wireless communication system. However,
through a frequency selective fading channel, the subcarriers
in MC-CDMA signal have different amplitude levels and phase
shifts which result in loss of the orthogonality among users
and generates Multiple access interference (MAI). To combat
the MAI, various amplitude and phase equalizing techniques
such as Maximum Ratio Combining (MRC), Equal Gain
Combining (EGC), Orthogonal Restoring Combining (ORC),
Threshold Orthogonal Restoring Combining or Minimum
Mean Square Error (MMSE) may be used. Out of these MMSE
offers better performance since the MMSE criterion is applied
independently on each subcarrier. Further improvement in
performance is possible through space–time block coding,
which offers maximum diversity gain and multiplexing gain.
This paper combines MC-CDMA with MMSE equalization
and space–time block coding which proves to be a powerful
physical layer solution in combating delay spread and inter
symbol interference (ISI).
Block diagonalization for Multi-user MIMO Beamforming Performance over Rician...IRJET Journal
This document discusses block diagonalization (BD) precoding performance in multi-user multiple-input multiple-output (MU-MIMO) beamforming systems over Rician fading channels. It begins with an abstract that introduces BD precoding as a linear precoding method for MU-MIMO broadcast channels that transmits interference-free data streams to multiple users by designing beamforming vectors. The document then evaluates BD precoding performance over both Rayleigh and Rician fading channels through simulation. The results show that the Rician fading channel provides better error rate performance than the Rayleigh channel, especially at low Rician factors.
BER Performance of MU-MIMO System using Dirty Paper CodingIJEEE
In this paper Dirty Paper Coding for communication system is implemented. MIMO application that involves devices such as cell phones, pocket PCs require closely spaced antenna, which suffers from mutual coupling among antennas and high spatial correlation for signals. DPC is used for compensating the degradation due to correlation and mutual coupling.
Average Channel Capacity of Amplify-and-forward MIMO/FSO Systems Over Atmosph...IJECEIAES
In amplify-and-forward (AF) relay channel, when the direct link between source and destination terminals is deeply faded, the signal from the source terminal to the destination terminal propagates through the relay terminals, each of which relays a signal received from the previous terminal to the next terminal in series. This paper, we theoretically analyze the performance of multiple-input multiple-output (MIMO) AF free-space optical (FSO) systems. The AF-MIMO/FSO average channel capacity (ACC), which is expressed in terms of average spectral efficiency (ASE) is derived taking into account the atmospheric turbulence effects on the MIMO/FSO channel. They are modeled by log-normal and the gamma-gamma distributions for the cases of weak-to-strong turbulence conditions. We extract closed form mathematical expression for the evaluation of the ACC and we quantitatively discuss the influence of turbulence strength, link distance, different number of relay stations and different MIMO configurations on it.
Performance Analysis of PAPR Reduction in MIMO-OFDMIJARBEST JOURNAL
Authors: Jayaraman.G1, VeeraKumar K2, Selvakani.S3
Abstract— In communication system, it is aimed to provide highest possible
transmission rate at the lowest possible power and with the least possible noise. MIMOOFDM
has been chosen for high data rate communications and widely deployed in many
wireless communication standards. The major drawback in OFDM signal transmission is
high PAPR. In previous, use clipping technique to tackle this problem. In this paper, use
EM-GAMP algorithm to reduce PAPR in considerable amount.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
MIMO Channel Estimation Using the LS and MMSE AlgorithmIOSRJECE
Wireless Communication Technology has developed over the past few yearsfor other objectives.The Multiple InputMultiple Output (MIMO) is one of techniques that is used to enhancethe data rates, in which multiple antennas are employed both the transmitter and receiver. Multiple signals are transmitted from different antennas at the transmitter using the same frequency and separated space. Various channel estimation techniques are employed in order to judge the physical effects of the medium present. In this paper, we analyze and implementvarious estimation techniques for MIMO Systems such as Least Squares (LS), Minimum Mean Square Error (MMSE),these techniques are therefore compared to effectively estimate the channel in MIMO System. The results demonstrate that SNR required to support different values of bit error rate varies depending on different low correlation between the transmitting and the receiving antennas .In addition, it is illustrated that when the number of transmitter and receiver antennas increases, the performance of TBCE schemes significantly improves. The Same behavior isalso observed for MIMO system. Performance of both MMSE and LSestimation are the same for allkinds of modulation at small value of SNR but the more we increase the SNR value the more performance gap goes on increasing.
This document analyzes the effects of carrier frequency offset (CFO) and fading branch correlation (FBC) on the performance of an asynchronous multi-carrier coded-division multiple-access (MC-CDMA) system. It establishes models for an MC-CDMA system with transmitter and receiver, and examines how CFO and FBC impact the bit error rate (BER) performance. Equations are derived relating CFO and FBC, and simulation results are presented showing which parameter, CFO or FBC, has a greater influence on system performance.
Full-duplex user-centric communication using non-orthogonal multiple accessTELKOMNIKA JOURNAL
This paper proposes an improved user-centric Non-Orthogonal Multiple Access (NOMA) communication in two-base station networks with in-band full duplex (IBFD) user. We derive the achievable rates of the proposed user-centric NOMA systems. For benchmarking purposes, we also derive the achievable rate for the user-centric system deploying conventional NOMA schemes, Orthogonal Multiple Access (OMA) schemes and point-point communication systems. We then analyze and simulate the performance of the proposed and all the benchmarked systems. We found that our proposed user-centric NOMA approach has a 64% improvement in the total achievable rate when compared to the benchmarked approach under similar power constraint.
With the rise of data-intensive mobile applications, network operators must find ways to increase network capacity to meet demand. MIMO (Multiple-Input Multiple-Output) techniques, which use multiple antennas at the transmission and reception ends, have the potential to significantly boost network throughput through spatial multiplexing. However, optimizing networks for MIMO's full benefits presents challenges, as MIMO works best under rich scattering conditions and requires accurate measurement of multipath environments. Real-world RF measurements tailored for MIMO networks can help operators overcome these challenges and maximize throughput gains from MIMO without additional spectrum or infrastructure.
Combining SFBC_OFDM Systems with SVD Assisted Multiuser Transmitter and Multi...IOSR Journals
Abstract: In this work, we exploit the SVD assisted multiuser transmitter (MUT) and multiuser detector (MUD) technique, using downlink (DL) preprocessing transmitter and DL postprocessing receiver matrice .In combination with space frequency block coding (SFBC). And also propose the precoded DL transmission scheme, were the both proposed schemes take advantage of the channel state information (CSI) of all users at the base station (BS), but only of the mobile station (MS)’s own CSI, to decompose the MU MIMO channels into parallel single input single output (SISO), these two proposed schemes are compared to the vertical layered space time (V_BLAST) combined with SFBC (SFBC_VBLAST). Our Simulation results show that the performance of the proposed scheme with DL Zero Forcing (ZF) transmitter for interference canceller outperforms the SFBC_VBLAST and the precoded DL schemes with ZF receiver in frequency selective fading channels. Keywords – Post processing, Preprocessing,, SFBC, SVD, ZF.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Iaetsd stbc-ofdm downlink baseband receiver for mobile wmanIaetsd Iaetsd
This document discusses a proposed space time block code-orthogonal frequency division multiplexing (STBC-OFDM) downlink baseband receiver for mobile wireless metropolitan area networks (WMANs). The proposed receiver applies STBC-OFDM techniques using two transmit antennas and one receive antenna to provide robust performance in outdoor mobile environments. It includes a simple and robust synchronizer and an accurate but affordable channel estimator to overcome challenges of multipath fading channels. Simulation results show the receiver can achieve a coded bit error rate of less than 10-6 for 16QAM modulation under vehicle speeds of 120 km/hr while supporting up to 27.32 Mb/s of uncoded data transmission. The receiver designed in a 90-nm CMOS
This document summarizes research on multi-numerology 5G new radio (NR) systems. It begins with an introduction comparing the flexibility of NR and LTE, noting that NR allows simultaneous use of multiple numerologies. Section II further describes differences in flexibility between NR and LTE regarding 3GPP standards. Section III then outlines potential research opportunities for improving multi-numerology systems, such as addressing interference between non-orthogonal numerologies. Finally, Section IV indicates that simulation results on inter-numerology interference will be presented as a function of guard allocation and parameters.
Computationally Efficient Multi-Antenna Techniques for Multi-User Two-Way Wire...IJECEIAES
In this work, we are interested in implementing, developing and evaluating multi-antenna techniques used for multi-user two-way wireless relay networks that provide a good tradeoff between the computational complexity and performance in terms of symbol error rate and achievable data rate. In particular, a variety of newly multi-antenna techniques is proposed and studied. Some techniques based on orthogonal projection enjoy low computational complexity. However, the performance penalty associated with them is high. Other techniques based on maximum likelihood strategy enjoy high performance, however, they suffer from very high computational complexity. The Other techniques based on randomization strategy provide a good trade-off between the computational complexity and performance where they enjoy low computational complexity with almost the same performance as compared to the techniques based on maximum likelihood strategy.
OFDM is a digital multi-carrier modulation technique that divides the available spectrum into multiple orthogonal subcarriers. It allows high spectral efficiency by spacing the carriers to maintain orthogonality even when their spectra overlap. The document provides an intuitive explanation of OFDM using analogies like a shower head vs faucet and multiple smaller trucks vs one large truck. It explains how OFDM provides resistance to interference by spreading data across orthogonal subcarriers rather than a single carrier. The key concept of orthogonality allows the subcarriers to overlap without interference by ensuring the area under one subcarrier's frequency multiplied by another is always zero.
This document summarizes a research paper on developing a reconfigurable hardware architecture for implementing maximum likelihood (ML) decoding algorithms in MIMO systems. It begins by introducing MIMO techniques for improving wireless communication throughput. It then describes various MIMO receiver algorithms and chooses ML for its best performance. The document outlines the ML decoding algorithm and presents a Simulink model. It discusses implementing the MIMO decoder as a modular, reconfigurable architecture on an FPGA and shows placement results on a Xilinx Virtex 4 chip. The work aims to provide flexible hardware for MIMO signal processing applications.
1. The document proposes a scheme called Superimposed Spatial Modulation (SSM) that allows for doubling of information conveyed in the spatial position of transmitting antennas.
2. SSM superimposes two independent spatial modulation systems on the same antenna array. Each system transmits different components of orthogonal symbols.
3. This approach increases spectral efficiency over conventional spatial modulation by doubling the size of the possible antenna constellations.
An Efficient Performance of Mimo - Ofdm Based Cognitieve Radio System for Arr...IOSR Journals
Abstract: The wireless channel is central within this context, thus estimating the channel is the key to make CR operational, taking in consideration that the transmission-reception technology is available. In this thesis, we design a MIMO system using OFDM modulation technology to transmit and receive two signals over the mobile wireless channel. First formulate the pilot design as a new optimization problem. We use MIMO concept to enhance system capacity and robustness of the wireless transmission. In Multi-Input Multi-Output (MIMO) based cognitive radio (CR) systems, with the increasing demand for data rate and reliability in Wireless communicationsand devices, several issues become very important like bandwidth efficiency, quality of service and radio coverage. In this new scheme, adaptive arrays are group-selected in the spatial domain. Simulation shows that the proposed system can get significant performance improvements over the conventional array based OFDM systems over frequency-selective multipath fading channels with cognitive radio (CR) system. Keywords: Cognitive radios, MIMO, OFDM, and Joint transmit and receive group selected arrays.
Classical Discrete-Time Fourier TransformBased Channel Estimation for MIMO-OF...IJCSEA Journal
In this document, we look at various time domain channel estimation methods with this constraint of null carriers at spectrumborders.We showin detail howto gauge the importance of the “border effect” depending on the number of null carriers, which may vary from one system to another. Thereby we assess the limit of the technique discussed when the number of null carriers is large. Finally the DFT with the truncated singular value decomposition (SVD) technique is proposed to completely eliminate the impact of the null subcarriers whatever their number. A technique for the determination of the truncation threshold for any MIMO-OFDM system is also proposed.
A Potent MIMO–OFDM System Designed for Optimum BER and its Performance Anal...inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Performance of the MIMO-MC-CDMA System with MMSE EqualizationTamilarasan N
Multipath fading and spectral crowding are the
major challenges in dealing higher data rate in future
broadband wireless communication system. Multi-carrier
Modulation like Multicarrier code division multiple access
(MC-CDMA) can tackle the problem and provide higher data
rate for future wireless communication system. However,
through a frequency selective fading channel, the subcarriers
in MC-CDMA signal have different amplitude levels and phase
shifts which result in loss of the orthogonality among users
and generates Multiple access interference (MAI). To combat
the MAI, various amplitude and phase equalizing techniques
such as Maximum Ratio Combining (MRC), Equal Gain
Combining (EGC), Orthogonal Restoring Combining (ORC),
Threshold Orthogonal Restoring Combining or Minimum
Mean Square Error (MMSE) may be used. Out of these MMSE
offers better performance since the MMSE criterion is applied
independently on each subcarrier. Further improvement in
performance is possible through space–time block coding,
which offers maximum diversity gain and multiplexing gain.
This paper combines MC-CDMA with MMSE equalization
and space–time block coding which proves to be a powerful
physical layer solution in combating delay spread and inter
symbol interference (ISI).
Block diagonalization for Multi-user MIMO Beamforming Performance over Rician...IRJET Journal
This document discusses block diagonalization (BD) precoding performance in multi-user multiple-input multiple-output (MU-MIMO) beamforming systems over Rician fading channels. It begins with an abstract that introduces BD precoding as a linear precoding method for MU-MIMO broadcast channels that transmits interference-free data streams to multiple users by designing beamforming vectors. The document then evaluates BD precoding performance over both Rayleigh and Rician fading channels through simulation. The results show that the Rician fading channel provides better error rate performance than the Rayleigh channel, especially at low Rician factors.
BER Performance of MU-MIMO System using Dirty Paper CodingIJEEE
In this paper Dirty Paper Coding for communication system is implemented. MIMO application that involves devices such as cell phones, pocket PCs require closely spaced antenna, which suffers from mutual coupling among antennas and high spatial correlation for signals. DPC is used for compensating the degradation due to correlation and mutual coupling.
Average Channel Capacity of Amplify-and-forward MIMO/FSO Systems Over Atmosph...IJECEIAES
In amplify-and-forward (AF) relay channel, when the direct link between source and destination terminals is deeply faded, the signal from the source terminal to the destination terminal propagates through the relay terminals, each of which relays a signal received from the previous terminal to the next terminal in series. This paper, we theoretically analyze the performance of multiple-input multiple-output (MIMO) AF free-space optical (FSO) systems. The AF-MIMO/FSO average channel capacity (ACC), which is expressed in terms of average spectral efficiency (ASE) is derived taking into account the atmospheric turbulence effects on the MIMO/FSO channel. They are modeled by log-normal and the gamma-gamma distributions for the cases of weak-to-strong turbulence conditions. We extract closed form mathematical expression for the evaluation of the ACC and we quantitatively discuss the influence of turbulence strength, link distance, different number of relay stations and different MIMO configurations on it.
Performance Analysis of PAPR Reduction in MIMO-OFDMIJARBEST JOURNAL
Authors: Jayaraman.G1, VeeraKumar K2, Selvakani.S3
Abstract— In communication system, it is aimed to provide highest possible
transmission rate at the lowest possible power and with the least possible noise. MIMOOFDM
has been chosen for high data rate communications and widely deployed in many
wireless communication standards. The major drawback in OFDM signal transmission is
high PAPR. In previous, use clipping technique to tackle this problem. In this paper, use
EM-GAMP algorithm to reduce PAPR in considerable amount.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
MIMO Channel Estimation Using the LS and MMSE AlgorithmIOSRJECE
Wireless Communication Technology has developed over the past few yearsfor other objectives.The Multiple InputMultiple Output (MIMO) is one of techniques that is used to enhancethe data rates, in which multiple antennas are employed both the transmitter and receiver. Multiple signals are transmitted from different antennas at the transmitter using the same frequency and separated space. Various channel estimation techniques are employed in order to judge the physical effects of the medium present. In this paper, we analyze and implementvarious estimation techniques for MIMO Systems such as Least Squares (LS), Minimum Mean Square Error (MMSE),these techniques are therefore compared to effectively estimate the channel in MIMO System. The results demonstrate that SNR required to support different values of bit error rate varies depending on different low correlation between the transmitting and the receiving antennas .In addition, it is illustrated that when the number of transmitter and receiver antennas increases, the performance of TBCE schemes significantly improves. The Same behavior isalso observed for MIMO system. Performance of both MMSE and LSestimation are the same for allkinds of modulation at small value of SNR but the more we increase the SNR value the more performance gap goes on increasing.
Effect on Channel Capacity of Multi-User MIMO System in Crowded AreaIJEEE
1) The document analyzes the effect of multi-user MIMO (MU-MIMO) systems on channel capacity in crowded urban areas compared to single-user MIMO (SU-MIMO) systems.
2) It finds that MU-MIMO can achieve higher channel capacity than SU-MIMO in urban environments due to lower spatial correlation between users, unlike assumptions of independent channels in MIMO transmission.
3) The improvement of MU-MIMO capacity over SU-MIMO increases with path visibility, with MU-MIMO showing better performance when path visibility is over 13%.
Joint impacts of relaying scheme and wireless power transfer in multiple acce...journalBEEI
This paper considers ergodic capacity of energy harvesting (EH) based cellular networks. Such a network employs non-orthogonal multiple access (NOMA) together with relaying scheme to serve two far users. In this system model, relay is facilitated power splitting (PS) protocol to implement energy harvesting (EH). To examine capacity, expressions of signal to noise ratio (SNR) need be computed to achieve capacity. Power allocation factors are different for two users in such system and hence performance gap happens to distinguish requirements for separated users. It can be confirmed that the proposed paradigm exhibits maximal achievable capacity in some scenarios of setting parameters. To confirm exactness of the analytical expressions and show advantages of the proposed EH-NOMA, simulation results are performed in terms of ergodic capacity.
ANALYTICAL PERFORMANCE EVALUATION OF A MIMO FSO COMMUNICATION SYSTEM WITH DIR...optljjournal
MIMO FSO correspondence is examined as of late to build up a hearty correspondence connects within the sight of atmospheric turbulence. In this paper an analytical approach is developed to assess the impact of atmospheric turbulence on BER performance of a MIMO FSO communication system with Q-ary Pulse Position Modulation (QPPM). Examination is exhibited to discover flag to clamor proportion at the yield of an immediate location collector with optical power modulator under strong turbulent condition which is modeled as gamma-gamma distribution. The outcomes demonstrate that the BER performance is emphatically debased because of the impact of atmospheric turbulence. In any case, the execution can be enhanced by expanding the quantity of transmitters, beneficiaries and request of Q in PPM. Results demonstrate that the FSO MIMO framework with M=8, N=4 Q=4 gives the 22 dB improvement at BER of 10-9 .
ANALYTICAL PERFORMANCE EVALUATION OF A MIMO FSO COMMUNICATION SYSTEM WITH DIR...optljjournal
MIMO FSO correspondence is examined as of late to build up a hearty correspondence connects within the
sight of atmospheric turbulence. In this paper an analytical approach is developed to assess the impact of
atmospheric turbulence on BER performance of a MIMO FSO communication system with Q-ary Pulse
Position Modulation (QPPM). Examination is exhibited to discover flag to clamor proportion at the yield
of an immediate location collector with optical power modulator under strong turbulent condition which is
modeled as gamma-gamma distribution. The outcomes demonstrate that the BER performance is
emphatically debased because of the impact of atmospheric turbulence
In this paper, we analyzed a numerical evaluation of the performance of MIMO radio systems in the LTE network environment. Downlink physical layer of the OFDM-MIMO based radio interface is considered for system model and a theoretical analysis of the bit error rate of the two space-time codes (SFBC 2×1 and FSTD 4×2 codes are adopted by the LTE norm as a function of the signal to noise ratio. Analytical expressions are given for transmission over a Rayleigh channel without spatial correlation which is then compared with Monte-Carlo simulations. Further evaluated channel capacity and simulation results show throughput almost reaches to the capacity limit.
Intersymbol interference caused by multipath in band limited frequency selective time dispersive channels distorts the transmitted signal, causing bit error at receiver. ISI is the major obstacle to high speed data transmission over wireless channels. Channel estimation is a technique used to combat the intersymbol interference. The objective of this paper is to improve channel estimation accuracy in MIMO-OFDM system by using modified variable step size leaky Least Mean Square (MVSSLLMS) algorithm proposed for MIMO OFDM System. So we are going to analyze Bit Error Rate for different signal to noise ratio, also compare the proposed scheme with standard LMS channel estimation method.
Tractable computation in outage performance analysis of relay selection NOMATELKOMNIKA JOURNAL
In recent years, using full-duplex (FD) transmission model provides enhanced bandwidth efficiency and improved performance for non-orthogonal multiple access (NOMA) system. However, lack of papers have investigated FD relay together with relay selection issue to improve performance of NOMA system. The problems in power allocation for two NOMA users satisfying fairness as well as relay selection strategy are studied in this paper. By considering the outage performance of proposed scheme with its vital result, general NOMA wireless networks can be developed for future networks due to its improved performance. Simulation results show that the relaying selection scheme can achieve a significant performance improvement by increasing required quantity of relay.
Index modulation is one of the promising techniques for future communications systems due to many improvement over the classical orthogonal frequency division multiplexing systems such as single RF chain, increased throughput for the same modulation order, achieved tradeoff between the efficiencies of the power and the spectral, and elimination of inter-channel interference. Many forms of index modulation researches exist where symbols are conveyed in antennas, subcarriers, time slots, and the space-time matrix. Spatial modulation is one member of index modulation family where symbols are conveyed in activating transmit/receive antennas. In this paper, a modification to a standard multiple input single output scheme by integrating spatial modulation using simplified mathematical procedure is achieved. In the transmitter side, data and activation symbols are distributed simultaneously using mathematical module and floor functions. At the receiver, a simplified maximum likelihood detector is used to obtain transmitted pair of symbols. To verify this, MATLAB simulink is used to simulate a downlink system where spatial modulation is applied to a base station. Results for different transmit antenna number and modulation order are obtained in the form of bit error rate versus signal to noise ratio.
This document summarizes a study that used two methods - nonlinear autoregressive neural network prediction (NARNN) and one-dimensional multilevel wavelet de-noising technique (1D MDT) - to predict path loss of GSM signals in an urban environment in Dnepropetrovsk, Ukraine. The NARNN had a mean square error of 3.3978dB while the 1D MDT had 3.428dB, showing the NARNN performed slightly better at 3.02%. Both methods predicted signal attenuation in the study area. Neural network clustering also revealed signal strengths between -75dB to -95dB were most common, indicating mostly weak signals were received.
IMPACT OF FADING CORRELATION, POLARIZATION COUPLING AND KEYHOLES ON MIMO DETE...ijmnct
This document summarizes a research paper that analyzes the impact of fading correlation, cross polarization coupling, and the keyhole effect on the error performance of V-BLAST MIMO systems using detectors like ZF, MMSE, and ML. It is observed that performance is better when channel fading correlation and cross polarization coupling values are lower. The keyhole effect can cause the channel matrix to be rank deficient, limiting the benefits of multiple antennas. Simulation results show the BER performance of these detectors for different modulation schemes under varying channel conditions.
This document summarizes a research paper that proposes and analyzes a beam selection algorithm called Interference Aware - Maximization of SINR (IA-MSS) selection for 5G millimeter-wave MIMO systems. The algorithm aims to maximize signal-to-interference ratio (SINR) by first classifying users into interference users and non-interference users based on their strongest beams, and then selecting beams to minimize multi-user interference while achieving high SINR. Analysis shows the IA-MSS algorithm achieves higher power efficiency than alternatives by exploiting sparse properties of beamspace channels in mmWave massive MIMO.
Turbo Detection in Rayleigh flat fading channel with unknown statisticsijwmn
The turbo detection of turbo coded symbols over correlated Rayleigh flat fading channels generated
according to Jakes’ model is considered in this paper. We propose a method to estimate the channel
signal-to-noise ratio (SNR) and the maximum Doppler frequency. These statistics are required by
the linear minimum mean squared error (LMMSE) channel estimator. To improve the system convergence, we redefine the channel reliability factor by taking into account the channel estimation
error statistics. Simulation results for rate 1/3 turbo code and two different normalized fading rates
show that the use of the new reliability factor greatly improves the performance. The improvement
is more substantial when channel statistics are unknown.
Analyses and performance of techniques papr reduction for stbc mimo ofdm syst...ijwmn
An OFDM system is combined with multiple-input mult
iple-output (MIMO) in order to increase the
diversity gain and system capacity over the time va
riant frequency-selective channels. However, a maj
or
drawback of MIMO-OFDM system is that the transmitte
d signals on different antennas might exhibit high
peak-to-average power ratio (PAPR).In this paper, w
e present a PAPR analysis reduction of space-time-
block-coded (STBC) MIMO-OFDM system for 4G wireless
networks. Several techniques have been used to
reduce the PAPR of the (STBC) MIMOOFDM system: clip
ping and filtering, partial transmit sequence
(PTS) and selected mapping (SLM). Simulation result
s show that clipping and filtering provides a bette
r
PAPR reduction than the others methods and only SLM
technique conserve the PAPR reduction in
reception part of signal.
Study on outage performance gap of two destinations on CR-NOMA networkTELKOMNIKA JOURNAL
This document studies the outage performance of two secondary destinations in a cognitive radio non-orthogonal multiple access (CR-NOMA) network. It presents a system model of a downlink dual-hop CR-NOMA network consisting of a primary destination, secondary source, relay, and two secondary destinations. It derives the exact outage probability expressions for the secondary users by obtaining the signal-to-interference-plus noise ratio and signal-to-noise ratio for each transmission. The results show that the performance gap between the two secondary users can be obtained due to different power allocation factors assigned to each user.
To meet the demands of high speed required by mobile communication of past generations ,one solution is
to increase the number of antennas to the show and the reception of the wireless link this is called MIMO
(Multiple input ,Multiple output )technology .however ,the integration of multiple antennas on the same
PCB is delicate because of the small volume that require some applications and electromagnetic antenna
between the coupling ,phenomena that we cannot neglect them .indeed a strong isolation between them has
been reached to reduce fading of the signal caused by the electromagnetic antenna reached to reduce
fading of the signal caused by the electromagnetic coupling and maximize the overall gain .in this article
we are interested then integration on the same printed circuit of eight antennas MIMO are not operation in
the same frequency band .the first antenna of this last work at 2.4GHz .other antennas have resonance
frequency folling each with 20MHz offset this device is characterized by its original form that keeps is
highly isolated antennas from the point of view electromagnetic coupling
Similar to BER Analysis for Downlink MIMO-NOMA Systems over Rayleigh Fading Channels (20)
Rendezvous Sequence Generation Algorithm for Cognitive Radio Networks in Post...IJCNCJournal
Recent natural disasters have inflicted tremendous damage on humanity, with their scale progressively increasing and leading to numerous casualties. Events such as earthquakes can trigger secondary disasters, such as tsunamis, further complicating the situation by destroying communication infrastructures. This destruction impedes the dissemination of information about secondary disasters and complicates post-disaster rescue efforts. Consequently, there is an urgent demand for technologies capable of substituting for these destroyed communication infrastructures. This paper proposes a technique for generating rendezvous sequences to swiftly reconnect communication infrastructures in post-disaster scenarios. We compare the time required for rendezvous using the proposed technique against existing methods and analyze the average time taken to establish links with the rendezvous technique, discussing its significance. This research presents a novel approach enabling rapid recovery of destroyed communication infrastructures in disaster environments through Cognitive Radio Network (CRN) technology, showcasing the potential to significantly improve disaster response and recovery efforts. The proposed method reduces the time for the rendezvous compared to existing methods, suggesting that it can enhance the efficiency of rescue operations in post-disaster scenarios and contribute to life-saving efforts.
Blockchain Enforced Attribute based Access Control with ZKP for Healthcare Se...IJCNCJournal
The relationship between doctors and patients is reinforced through the expanded communication channels provided by remote healthcare services, resulting in heightened patient satisfaction and loyalty. Nonetheless, the growth of these services is hampered by security and privacy challenges they confront. Additionally, patient electronic health records (EHR) information is dispersed across multiple hospitals in different formats, undermining data sovereignty. It allows any service to assert authority over their EHR, effectively controlling its usage. This paper proposes a blockchain enforced attribute-based access control in healthcare service. To enhance the privacy and data-sovereignty, the proposed system employs attribute-based access control, zero-knowledge proof (ZKP) and blockchain. The role of data within our system is pivotal in defining attributes. These attributes, in turn, form the fundamental basis for access control criteria. Blockchain is used to keep hospital information in public chain but EHR related data in private chain. Furthermore, EHR provides access control by using the attributed based cryptosystem before they are stored in the blockchain. Analysis shows that the proposed system provides data sovereignty with privacy provision based on the attributed based access control.
EECRPSID: Energy-Efficient Cluster-Based Routing Protocol with a Secure Intru...IJCNCJournal
A revolutionary idea that has gained significance in technology for Internet of Things (IoT) networks backed by WSNs is the " Energy-Efficient Cluster-Based Routing Protocol with a Secure Intrusion Detection" (EECRPSID). A WSN-powered IoT infrastructure's hardware foundation is hardware with autonomous sensing capabilities. The significant features of the proposed technology are intelligent environment sensing, independent data collection, and information transfer to connected devices. However, hardware flaws and issues with energy consumption may be to blame for device failures in WSN-assisted IoT networks. This can potentially obstruct the transfer of data. A reliable route significantly reduces data retransmissions, which reduces traffic and conserves energy. The sensor hardware is often widely dispersed by IoT networks that enable WSNs. Data duplication could occur if numerous sensor devices are used to monitor a location. Finding a solution to this issue by using clustering. Clustering lessens network traffic while retaining path dependability compared to the multipath technique. To relieve duplicate data in EECRPSID, we applied the clustering technique. The multipath strategy might make the provided protocol more dependable. Using the EECRPSID algorithm, will reduce the overall energy consumption, minimize the End-to-end delay to 0.14s, achieve a 99.8% Packet Delivery Ratio, and the network's lifespan will be increased. The NS2 simulator is used to run the whole set of simulations. The EECRPSID method has been implemented in NS2, and simulated results indicate that comparing the other three technologies improves the performance measures.
Analysis and Evolution of SHA-1 Algorithm - Analytical TechniqueIJCNCJournal
A 160-bit (20-byte) hash value, sometimes called a message digest, is generated using the SHA-1 (Secure Hash Algorithm 1) hash function in cryptography. This value is commonly represented as 40 hexadecimal digits. It is a Federal Information Processing Standard in the United States and was developed by the National Security Agency. Although it has been cryptographically cracked, the technique is still in widespread usage. In this work, we conduct a detailed and practical analysis of the SHA-1 algorithm's theoretical elements and show how they have been implemented through the use of several different hash configurations.
Optimizing CNN-BiGRU Performance: Mish Activation and Comparative AnalysisIJCNCJournal
Deep learning is currently extensively employed across a range of research domains. The continuous advancements in deep learning techniques contribute to solving intricate challenges. Activation functions (AF) are fundamental components within neural networks, enabling them to capture complex patterns and relationships in the data. By introducing non-linearities, AF empowers neural networks to model and adapt to the diverse and nuanced nature of real-world data, enhancing their ability to make accurate predictions across various tasks. In the context of intrusion detection, the Mish, a recent AF, was implemented in the CNN-BiGRU model, using three datasets: ASNM-TUN, ASNM-CDX, and HOGZILLA. The comparison with Rectified Linear Unit (ReLU), a widely used AF, revealed that Mish outperforms ReLU, showcasing superior performance across the evaluated datasets. This study illuminates the effectiveness of AF in elevating the performance of intrusion detection systems.
An Hybrid Framework OTFS-OFDM Based on Mobile Speed EstimationIJCNCJournal
The Future wireless communication systems face the challenging task of simultaneously providing high-quality service (QoS) and broadband data transmission, while also minimizing power consumption, latency, and system complexity. Although Orthogonal Frequency Division Multiplexing (OFDM) has been widely adopted in 4G and 5G systems, it struggles to cope with a significant delay and Doppler spread in high mobility scenarios. To address these challenges, a novel waveform named Orthogonal Time Frequency Space (OTFS). Designers aim to outperform OFDM by closely aligning signals with the channel behaviour. In this paper, we propose a switching strategy that empowers operators to select the most appropriate waveform based on an estimated speed of the mobile user. This strategy enables the base station to dynamically choose the waveform that best suits the mobile user’s speed. Additionally, we suggest retaining an Integrated Sensing and Communication (ISAC) radar approach for accurate Doppler estimation. This provides precise information to facilitate the waveform selection procedure. By leveraging the switching strategy and harnessing the Doppler estimation capabilities of an ISAC radar.Our proposed approach aims to enhance the performance of wireless communication systems in high mobility cases. Considering the complexity of waveform processing, we introduce an optimized hybrid system that combines OTFS and OFDM, resulting in reduced complexity while still retaining performance benefits.This hybrid system presents a promising solution for improving the performance of wireless communication systems in higher mobility.The simulation results validate the effectiveness of our approach, demonstrating its potential advantages for future wireless communication systems. The effectiveness of the proposed approach is validated by simulation results as it will be illustrated.
Enhanced Traffic Congestion Management with Fog Computing - A Simulation-Base...IJCNCJournal
Accurate latency computation is essential for the Internet of Things (IoT) since the connected devices generate a vast amount of data that is processed on cloud infrastructure. However, the cloud is not an optimal solution. To overcome this issue, fog computing is used to enable processing at the edge while still allowing communication with the cloud. Many applications rely on fog computing, including traffic management. In this paper, an Intelligent Traffic Congestion Mitigation System (ITCMS) is proposed to address traffic congestion in heavily populated smart cities. The proposed system is implemented using fog computing and tested in a crowdedCairo city. The results obtained indicate that the execution time of the simulation is 4,538 seconds, and the delay in the application loop is 49.67 seconds. The paper addresses various issues, including CPU usage, heap memory usage, throughput, and the total average delay, which are essential for evaluating the performance of the ITCMS. Our system model is also compared with other models to assess its performance. A comparison is made using two parameters, namely throughput and the total average delay, between the ITCMS, IOV (Internet of Vehicle), and STL (Seasonal-Trend Decomposition Procedure based on LOESS). Consequently, the results confirm that the proposed system outperforms the others in terms of higher accuracy, lower latency, and improved traffic efficiency.
Rendezvous Sequence Generation Algorithm for Cognitive Radio Networks in Post...IJCNCJournal
Recent natural disasters have inflicted tremendous damage on humanity, with their scale progressively increasing and leading to numerous casualties. Events such as earthquakes can trigger secondary disasters, such as tsunamis, further complicating the situation by destroying communication infrastructures. This destruction impedes the dissemination of information about secondary disasters and complicates post-disaster rescue efforts. Consequently, there is an urgent demand for technologies capable of substituting for these destroyed communication infrastructures. This paper proposes a technique for generating rendezvous sequences to swiftly reconnect communication infrastructures in post-disaster scenarios. We compare the time required for rendezvous using the proposed technique against existing methods and analyze the average time taken to establish links with the rendezvous technique, discussing its significance. This research presents a novel approach enabling rapid recovery of destroyed communication infrastructures in disaster environments through Cognitive Radio Network (CRN) technology, showcasing the potential to significantly improve disaster response and recovery efforts. The proposed method reduces the time for the rendezvous compared to existing methods, suggesting that it can enhance the efficiency of rescue operations in post-disaster scenarios and contribute to life-saving efforts.
Vehicle Ad Hoc Networks (VANETs) have become a viable technology to improve traffic flow and safety on the roads. Due to its effectiveness and scalability, the Wingsuit Search-based Optimised Link State Routing Protocol (WS-OLSR) is frequently used for data distribution in VANETs. However, the selection of MultiPoint Relays (MPRs) plays a pivotal role in WS-OLSR's performance. This paper presents an improved MPR selection algorithm tailored to WS-OLSR, designed to enhance the overall routing efficiency and reduce overhead. The analysis found that the current OLSR protocol has problems such as redundancy of HELLO and TC message packets or failure to update routing information in time, so a WS-OLSR routing protocol based on improved-MPR selection algorithm was proposed. Firstly, factors such as node mobility and link changes are comprehensively considered to reflect network topology changes, and the broadcast cycle of node HELLO messages is controlled through topology changes. Secondly, a new MPR selection algorithm is proposed, considering link stability issues and nodes. Finally, evaluate its effectiveness in terms of packet delivery ratio, end-to-end delay, and control message overhead. Simulation results demonstrate the superior performance of our improved MR selection algorithm when compared to traditional approaches.
May 2024, Volume 16, Number 3 - The International Journal of Computer Network...IJCNCJournal
The International Journal of Computer Networks & Communications (IJCNC) is a bi monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Computer Networks & Communications. The journal focuses on all technical and practical aspects of Computer Networks & data Communications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced networking concepts and establishing new collaborations in these areas.
Vehicle Ad Hoc Networks (VANETs) have become a viable technology to improve traffic flow and safety on the roads. Due to its effectiveness and scalability, the Wingsuit Search-based Optimised Link State Routing Protocol (WS-OLSR) is frequently used for data distribution in VANETs. However, the selection of MultiPoint Relays (MPRs) plays a pivotal role in WS-OLSR's performance. This paper presents an improved MPR selection algorithm tailored to WS-OLSR, designed to enhance the overall routing efficiency and reduce overhead. The analysis found that the current OLSR protocol has problems such as redundancy of HELLO and TC message packets or failure to update routing information in time, so a WS-OLSR routing protocol based on improved-MPR selection algorithm was proposed. Firstly, factors such as node mobility and link changes are comprehensively considered to reflect network topology changes, and the broadcast cycle of node HELLO messages is controlled through topology changes. Secondly, a new MPR selection algorithm is proposed, considering link stability issues and nodes. Finally, evaluate its effectiveness in terms of packet delivery ratio, end-to-end delay, and control message overhead. Simulation results demonstrate the superior performance of our improved MR selection algorithm when compared to traditional approaches.
A Novel Medium Access Control Strategy for Heterogeneous Traffic in Wireless ...IJCNCJournal
So far, Wireless Body Area Networks (WBANs) have played a pivotal role in driving the development of intelligent healthcare systems with broad applicability across various domains. Each WBAN consists of one or more types of sensors that can be embedded in clothing, attached directly to the body, or even implanted beneath an individual's skin. These sensors typically serve asingle application. However, the traffic generated by each sensor may have distinct requirements. This diversity necessitates a dual approach: tailored treatment based on the specific needs of each traffic typeand the fulfillment of application requirements, such asreliability and timeliness. Never the less, the presence of energy constraints and the unreliable nature of wireless communications make QoS provisioning under such networks a non-trivial task. In this context, the current paper introduces a novel Medium AccessControl (MAC) strategy for the regular traffic applications of WBANs, designed to significantly enhance efficiency when compared to the established MAC protocols IEEE 802.15.4 and IEEE 802.15.6, with a particular focus on improving reliability, timeliness, and energy efficiency.
May_2024 Top 10 Read Articles in Computer Networks & Communications.pdfIJCNCJournal
The International Journal of Computer Networks & Communications (IJCNC) is a bi monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Computer Networks & Communications. The journal focuses on all technical and practical aspects of Computer Networks & data Communications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced networking concepts and establishing new collaborations in these areas.
A Topology Control Algorithm Taking into Account Energy and Quality of Transm...IJCNCJournal
The efficient use of energy in wireless sensor networks is critical for extending node lifetime. The network topology is one of the factors that have a significant impact on the energy usage at the nodes and the quality of transmission (QoT) in the network. We propose a topology control algorithm for software-defined wireless sensor networks (SDWSNs) in this paper. Our method is to formulate topology control algorithm as a nonlinear programming (NP) problem with the objective to optimizing two metrics, maximum communication range, and desired degree. This NP problem is solved at the SDWSN controller by employing the genetic algorithm (GA) to determine the best topology. The simulation results show that the proposed algorithm outperforms the MaxPower algorithm in terms of average node degree and energy expansion ratio.
Multi-Server user Authentication Scheme for Privacy Preservation with Fuzzy C...IJCNCJournal
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BER Analysis for Downlink MIMO-NOMA Systems over Rayleigh Fading Channels
1. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.6, November 2021
DOI: 10.5121/ijcnc.2021.13606 93
BER ANALYSIS FOR DOWNLINK MIMO-NOMA
SYSTEMS OVER RAYLEIGH FADING CHANNELS
Vu Tran Hoang Son1, 2
and Dang Le Khoa1,2*
1
VNUHCM - University of Science, Ho Chi Minh City, Vietnam
2
Vietnam National University, Ho Chi Minh City, Vietnam
ABSTRACT
The Multiple-input multiple-output (MIMO) technique combined with non-orthogonal multiple access
(NOMA) has been considered to enhance total system performance. This paper studies the bit error rate of
two-user power-domain NOMA systems using successive interference cancellation receivers, with zero-
forcing equalization over quasi-static Rayleigh fading channels. Successive interference cancellation
technique at NOMA receivers has been the popular research topic due to its simple implementation,
despite its vulnerability to error propagation. Closed-form expressions are derived for downlink NOMA in
single-input single-output and uncorrelated quasi-static MIMO Rayleigh fading channel. Analytical results
are consolidated with Monte Carlo simulation.
KEYWORDS
Bit error rate, Multiple-input multiple-output, non-orthogonal multiple access.
1. INTRODUCTION
Recent communication systems aim to meet the high capacity requirements. Non-orthogonal
multiple access (NOMA) is not only available in conventional 4G, recommended in 5G and
future 6G due to many outstanding benefits [1, 2]. NOMA can be divided into two main
categories as power-domain NOMA and code-domain NOMA. Successive interference
cancellation (SIC) is well-known in power-domain NOMA systems for its simple
implementation, although it has low performance compared to other detection techniques such as
using log-likelihood ratios[3], or machine learning[4, 5]. There have been many studies in the
probability of outage[6], power allocation[7], system capacity [8], bit error rate (BER)[9-13],
showing that NOMA is superior to conventional orthogonal multiple access[14]. NOMA can be
integrated with multiple input, multiple output(MIMO), which can result in a notable increase in
capacity[15], or even combined with deep neural network and beam forming [16]. To the best of
the authors' knowledge, there is no approach to BER expressions when changing between
multiuser superposition transmission (MUST) categories in 3GPP LTE Release 13 [17, 18] to
generate NOMA signals. The main contributions of this paper are:
1) Closed-form BER expressions for NOMA in two-user scenario with quadrature phase
shift keying(QPSK) modulation over quasi-static single-input single-output (SISO)
Rayleigh fading channels are investigated.
2) Under certain conditions, BER expressions perfectly suit the MIMO case. This is verified
via Monte Carlo simulation.
3) When Rayleigh channel has multiple taps, simulations barely fit analytical results due to
the limited response of zero-forcing(ZF) equalization. Because of this, via simulations,
authors have combined the conventional systems with orthogonal frequency division
2. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.6, November 2021
94
multiplexing (OFDM) to reduce inter-symbol interference (ISI), regardless of non-
linearities.
From this section, the paper is organized as follows. Section 2 presents and compares with related
work in the same field. Section 3 introduces the system model and the corresponding parameters.
Based on preexisting papers, Section 4 analyzes BER in MUST category 1. Section 5 proceeded
to MUST category 2 with a different approach, giving unified results when applying in MUST
category 1. Section 6 considered the effect of MIMO in NOMA systems, under certain
constraints, compared to SISO. All expressions are verified in Section 7 via simulations, and
conclusions along with future works are drawn in Section 8.
2. RELATED WORK
BER is one of the key factors to evaluate MIMO-NOMA system performance. This section will
consider related work that analyzes BER in the NOMA system. In [9], BER expressions of uplink
NOMA with SIC receivers has been derived over Additive White Gaussian Noise(AWGN)
channels. In [10], F. Kara has developed BER expressions for downlink NOMA over Rayleigh
fading channels with two users: far user (FU) using binary phase shift keying (BPSK), and near
user (NU) using QPSK. All expressions are followed by simulations. With significant effort, T.
Assaf et al. have introduced analytical BER through Nakagami-m fading channels in scenarios of
two and three users with QPSK modulation in [11], and through AWGN channels with general
M-QAM modulation[13].The authors in [12] investigated BER in QPSK-modulated NOMA
users on the AWGN channel and verified by software defined radio platforms. Similar research in
recent papers shows that NOMA signals are generated using only MUST type 1 and are limited
in SISO systems. Moreover, in the following years, applications of MIMO, or even massive
MIMO (m-MIMO), will be in new generation mobile networks. Our research is to find out the
BER analysis approach united in both MUST type 1 and type 2 in SISO systems, propose a
comparison with MIMO in Rayleigh fading channels, using Monte Carlo simulations to validate
the results.
3. SYSTEM MODEL
3.1. Downlink NOMAsystem
Consider downlink SISO-NOMA system with two user’s equipment (UEs) and a base station
(BS) as depicted in Figure 1.
Figure 1. Downlink SISO-NOMA system
3. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.6, November 2021
95
BS will generate NOMA signals using MUST cat.1 or MUST cat.2 [17, 18]. Based on Figure 1,
the generated signal sc
x can be expressed as
1 1 2 2
sc
x P x P x
, (3.1)
where k
x and k
P are respectively kth user’s signals and power allocation coefficients using
QPSK modulation, with BS transmitted power S
P and power allocation ratio satisfies
1 2
S
P P P
, 1 S
P P
,
2 1 S
P P
. For users’ fairness, near user (NU) UE1 will be allocated
less power than far user (FU) UE2, which means 1 2
P P
or 0 0.5
.
For quasi-static fading channel, the received signal at user kth can be described as[19, 20]
k k sc k
y = h x +n , (3.2)
where k
y is the received signal matrix, k
h is the uncorrelated quasi-static Rayleigh channel
matrix with
0,
k k
g
h CN , k
g is the average channel gain
2
E
k k
g
h , k
n is circularly
symmetric white Gaussian noise with
0
0,
k N
n CN , " "
is the convolution operator which can
be reduced to inner product when the channel is single-tap,
E . is the expected value,
2
. is the
Euclidean norm.
SIC process will be conducted at NU. NU will estimate FU’s symbols and use SIC to eliminate
interference by subtracting FU’s symbols from the received signal, then NU decodes its own
symbols. On the other hand, FU does not need to apply SIC, instead detect its symbols by
considering others as noise.
3.2. MIMO-NOMA system
One of the techniques in MIMO is spatial division multiplexing (SDM), which takes advantage of
the multipath channel to enhance system capacity without increasing the bandwidth. Figure 2
presents a downlink MIMO-NOMA system using SDM 2x2.
Figure 2. Downlink MIMO-NOMA system
4. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.6, November 2021
96
Because the UEs are identical, we will investigate a general MIMO SDM 2x2 case as Figure 3.
Figure 3. MIMO SDM 2x2 system
If the spacing between the transmitting and receiving antennas is large enough, the scattering
characteristics will be uncorrelated, so each path is independent. Under these conditions, the
desired signal from the target transmitting antenna can be detected by treating other transmitted
signals as interferences. This is called linear signal detection. We will concentrate on the
technique that nullifies the interference, zero-forcing method. From Figure 3, the received signal
matrix can be expressed as [21]
1 1 2 2
m m
= m + z = +
y h h h + z , (3.3)
whereh denotes an uncorrelated MIMO 2x2 Rayleigh channel matrix with
, th
j i entry ji
h for
the single-tap channel gain between the th
i transmit antenna and the th
j receive antenna,
1,2
j and 1,2
i , then 21
12 2
11
2
h h
h h
h .The spatially multiplexed data and the corresponding
received signals in a symbol time are represented by
1 2
,
T
m m
m and
1 2
,
T
y y
y ,
respectively, where i
m is the message from the th
i transmit antenna, j
y is the received signal at
the th
j receive antenna,
.
T
is the matrix transpose operation. The transmission power of each
antenna is assumed to be one. Let
1 2
,
T
z z
z with j
z denote the circularly symmetric white
Gaussian noise with a variance of 2
z
at the th
j receive antenna, and i
h denote the th
i column
vector of the channel matrix h .
The effect of the channel is inverted by a weight matrix w that
1 2
,
T
m m
m wy , therefore,
we can detect the desired signals from each antenna. The ZF technique nullifies the interference
by the weight matrix
1
H H
ZF
w h h h with
.
H
is the Hermitian transpose operation. All
formulas here can be used in the time domain and inner product because of single-tap channel
assumptions, but when the channel is multiple-tap, all quantities need to be in the frequency
domain via the Fourier transform. Received signals after ZF equalization is
1
.
ZF
H H
ZF
m z
m w y
h h h
z
m
(3.4)
5. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.6, November 2021
97
As seen in (3.4), each original data stream is separated from the multiplexed signal. After
equalization, every UE (except the strongest one) detects its information using SIC process.
Notice that if the channel has only one tap, a complex h can be presented in the form of
amplitude and phase, such for SISO case that
exp
R I
h h jh h j
h with 2
1
j ,
2 2
R I
h h h
is the magnitude of h , is the argument of h ,then ZF can be implemented
by[10, 21]
2
2
exp
exp .
y y
conj h
h h
y
h j
h
n
x j
h
(3.5)
From (3.5), n and
exp
n j
is different by a phase shift, however, n is circularly symmetric
so n and
exp
n j
have the same probability distribution. This is one of the key factors to
form the composite reference constellation discussed later in Section 4 and Section 0.
4. BER IN MUST CATEGORY 1
Based on (3.5), Figure 4shows the reference constellation to detect signals at each UE when using
MUST category 1. Red bits denote FU’s bits, and black bits are NU’s bits. The order of bits is
ascending, where the most significant bit is leftmost and is stated as the first bit.
Figure 4. Reference constellation at the receiver when using MUST cat.1
6. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.6, November 2021
98
4.1. BER of Far User
As seen in Figure 4, the first bit of UE2, which relies only on the in-phase component, will be
detected erroneously when one of these following cases occurs.
2 1
2 0
2 2
I
P P
n h
(4.1)
2 1
2 0
2 2
I
P P
n h
. (4.2)
Considering the second bit of UE2, which depends only on the quadrature component of the
signal, we see that the error cases are identical to (4.1) and (4.2). Assume the prior probability of
0’s and 1’s bit is equal, so the prior probability of each symbol is also equal. The symmetry
between in-phase and quadrature components of the symbol allows us to investigate only one of
them. Therefore, the variance of considered AWGN now is only half of the total noise, e.g.,
0
0,
2
I
N
n
N . By considering maximum likelihood detection rule, scaling
.
Q function, the
error probability of the FU symbols is
2 1 2 1
2 2
2
0 0
2 2 2 2
1 1
2 2
2 2
P P P P
h h
P e Q Q
N N
. (4.3)
Define some notations as
2 2
2 1 2
0
A
P P h
N
2 2
2 1 2
0
E
A
P P h
N
(4.4)
2 2
2 1 2
0
B
P P h
N
2 2
2 1 2
0
E
B
P P h
N
.
In the case of quasi-static Rayleigh channel, using [10, 20, 22] with (4.4), the average BER
expression of UE2 is defined as
2
1
1 1
4 2 2
A B
A B
P e
. (4.5)
4.2. BER of Near User
Based on [10-13], this section proposes an approach to derive BER of NU. Due to the SIC
process, NU detection must be considered under the condition of FU detection. On the other
hand, in Figure 4, if the second bit of FU is in error, it has no effect on the decision of NU first
bit. Hence, there are two situations: The FU first bit is error-free and in error.
Case 1: When FU is error-free at NU, from Figure 4, yields:
7. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.6, November 2021
99
2 1
2 1
correct Pr
2 2
a I
P P
P n h
(4.6)
2 1
2 1
correct Pr
2 2
b I
P P
P n h
. (4.7)
After SIC process, the reference constellation for NU is given in Figure 5 [12, 13]
Figure 5. Reference constellation for NU after SIC when FU is error-free
From (4.6), (4.7) and 5, the error probabilities of NU are conditional probabilities as
1 2 1
1 1 2 1 1
correct Pr
2 2 2
I I
P P P
P e n h n h
(4.8)
1 2 1
1 2 2 1 1
correct Pr
2 2 2
I I
P P P
P e n h n h
. (4.9)
Applying Bayes’ theorem, we have the total error probability of NU if FU is detected correctly
1 2 2 1 1 2 2 1 2 2
1 2 1 1
1 1 1
1 1 2 1
1
0 0
1
correct correct correct correct correct
2
1
Pr Pr
2 2 2 2 2
1
2
a b
I I
P P P e P P e
P P P P
h n h n h
P h P P
Q Q h
N N
.
(4.10)
Case 2: When FU is in error at NU, from Figure 4, we have:
2 1
2 1
error Pr
2 2
a I
P P
P n h
(4.11)
8. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.6, November 2021
100
2 1
2 1
1
error Pr
2 2 2
b I
P P
P n h
. (4.12)
Assume that the first bit of UE2 being transmitted is 0’ but detected as 1’, after the SIC process,
the reference constellation of NU is given in Figure 6.
Figure 6. Reference constellation for NU after SIC when FU is erroneously detected
From (4.11), (4.12) and Figure 6, the error probability of NU when FU is in error consists of
2 1 2 1
1 1 2 1 1
2
error Pr
2 2
2
I I
P P P P
P e n h n h
(4.13)
2 1 2 1
1 2 2 1 1
2
error Pr
2 2
2
I I
P P P P
P e n h n h
. (4.14)
In a similar way to (4.10), the total error probability of NU when FU is erroneously detected is
obtained as
1 2 2 1 1 2 2 1 2 2
2 1 2 1 2 1
1 1 1
2 1 2 1 2 1
1 1
0 0 0
1
error error error error error
2
2 2
1
Pr Pr
2 2 2 2
2 2
1 1 1
2 2 2
a b
I I
P P P e P P e
P P P P P P
n h h n h
P P P P P P
Q h Q h Q
N N N
1 .
h
(4.15)
From (4.10) and (4.15), the total error probability of NU is followed by
9. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.6, November 2021
101
1 1 2 1 2
1 1 2 1 2 1
1 1
0 0 0
2 1 2 1
1 1
0 0
correct error
1
2
2 2
1
.
2
P e P P
P h P P P P
Q Q h Q h
N N N
P P P P
Q h Q h
N N
(4.16)
Define some notations
2
1 1
0
C
P h
N
2
1 1
0
C
P E h
N
(4.17)
2 2
2 1 1
0
D
P P h
N
2 2
2 1 1
0
D
P P E h
N
2 2
2 1 1
0
E
P P h
N
2 2
2 1 1
0
E
P P E h
N
2 2
2 1 1
0
2
F
P P h
N
2 2
2 1 1
0
2
F
P P E h
N
2 2
2 1 1
0
2
G
P P h
N
2 2
2 1 1
0
2
.
G
P P E h
N
.
Hence, the average BER of NU over quasi-static Rayleigh channel is expressed as
1
1 1
1
2 4
2 2 2 2 2
C G
D E F
C D E F G
P e
. (4.18)
5. BER IN MUST CATEGORY 2
Figure 7 shows the reference constellation to detect signals at each UE when using MUST
category 2. Red bits denote FU’s bits, and black bits are NU’s bits. The order of bits is ascending,
where the most significant bit is leftmost and is stated as the first bit. Gray-coded mapping is
conserved for adjacent symbols.
10. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.6, November 2021
102
Figure 7. Reference constellation at the receiver when using MUST cat.2
5.1. BER of Far User
For MUST cat.2, from Figure 7, mapping rules for FU’s bits remains unchanged comparing to
MUST cat.1. Therefore, BER expressions of UE2 in this case are identical to (4.3) and (4.5).
5.2. BER of Near User
In this section, authors proposed another approach to analyze BER of NU, different from Section
4.2 and [10-13]. For UE1, error probabilities depend on the last two bits of a symbol. As a result
of constellation symmetry and equal prior probabilities, the third and fourth bits are the same in
error probabilities. The third bit is in error when one of these cases happens
2 1
2
1 1 0
2 2
I
P P
P
h n h
2 1 2
1 1
2
2
I
P P P
n h h
(5.1)
2 1 2
1 1
0
2
2
I
P P P
n h h
2 1 2
1 1
2
2
I
P P P
n h h
.
The error probability of NU calculated from (5.1) is
1 1 2 1 2 1
1 3 1 1
0 0 0
2 2
1
.
2
b
P h P P P P
P e P e Q Q h Q h
N N N
(5.2)
And the average BER expression of NU over the quasistatic Rayleigh channel is given by (5.3),
with notation in (4.17)
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103
1
1 1
1
2 4
2 2 2
C G
F
C F G
P e
. (5.3)
If we use the above approach for MUST cat.1, UE1 BER expressions obtain the same result as
(4.16) and (4.18)[12, 13]. Compare (4.16) and (5.2) or (4.18) and (5.3), a BER expression of
MUST cat.2 has only three out of five components of MUST cat.1, hopefully leading to lower
BER.
6. BER IN MIMO-NOMA
As derived in Section 3.2, we have the equalized signal, more specifically expressed as[19, 21]
1
1
2
H H
m
m
ZF
m z h h
m h z . (6.1)
Each receiving antenna has two data streams that are perfectly separated when the channel is not
correlated with the ideal ZF. Now consider the effect of ZF on AWGN. We have the singular
value decomposition (SVD) for the MIMO 2x2 channel is H
h UΣV , where 2x2
U and
2x2
V are unitary matrices, 2x2
Σ is a rectangular matrix whose diagonal elements are non-
negative real numbers and whose off-diagonal elements are zero. The diagonal elements of Σ are
the singular values of the matrix h , denoting them as 1
, 2
, so 2
1
and 2
2
are eigen values.
Then, (6.1) can be rewritten
1
2
1
2
1
1
.
H H H H
H
H
m
m
m
m
UΣV UΣV UΣV
VΣ
z
U
m
z
(6.2)
From (6.2), for uncorrelated MIMO channels, eigenvectors are linearly independent leading to
their singular values are non-zero and non-repeated, the expected value of noise power at fixed
eigen values is given as [21]
2 2 2
2
2
2 2 2
MIMO
1 1 2
z z z
i i
E
ZF
z . (6.3)
If 2 2
1 2
, equation (6.3) can be approximated
2 2
2
2
2 2
MIMO
1 1
z z
i i
E
ZF
z . (6.4)
From (6.4), we can see that each antenna in the introduced MIMO encounters the same effect as
SISO channel with the corresponding eigen value 2
1
. If the condition number of the channel
matrix is getting larger than a threshold, then the minimum singular value is very small, which
makes the approximation be more precise. For MIMO T R
N N
channel matrix where T R
N N
denoting the number of transmit and receive antennas respectively,
2 2 2 2
min 1 2
min , ,..., T
N
,
followed by (6.5)
12. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.6, November 2021
104
2 2
2
2 2
MIMO
1 min
T
N
z z
i i
E
ZF
z . (6.5)
7. NUMERICALAND SIMULATION RESULTS
In this section, the authors used Monte Carlo simulation over independent symbols to verify all
proposed expressions, under different power allocation ratios and MUST types corresponding to
the model in Figure 1 and Figure 2. Simulation parameters are specified in Table 1.
Table 1. Simulation parameters for single tap fading channels
Parameter Value
UE1’s average channel gain
2
1 1
E 1
g
h
UE2’s average channel gain
2
2 2
E 0.5
g
h
Power allocation ratio
0.2;0.3
Single antenna transmission power 1
S
P
Channel information Perfectly known at receivers
Equalization method ZF
Fading channel
Single-tap Rayleigh
SISO, uncorrelated MIMO
Figure 8 shows the BER results when using MUST cat.1 in SISO-NOMA systems where 0.2
and 0.3
, corresponding to
1 2
; 0.2;0.8
P P and
1 2
; 0.3;0.7
P P respectively. All
proposed expressions perfectly match the simulation results for both cases, as equation (4.5) for
UE2 and equation (4.18) for UE1. Under given channel conditions, BER of two users in 0.2
is better than 0.3
. At optimum power allocation, if increasing , which decreases UE2’s
power allocation coefficient, it leads to the degradation of the BER in UE2. In such a case,
although UE1 is allocated more power, its BER is not better but on the trend of getting worse, the
reason is that UE1’s symbol detection depends on UE2’s decoding.
Figure 8. BER of two users in SISO-NOMA using MUST cat.1 with different power allocation ratios
13. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.6, November 2021
105
Figure 9 changes to MUST cat.2 in MIMO-NOMA systems with 0.2
and 0.3
. Results
show that MIMO has the same BER performance as SISO under certain restraints, with BER of
UE1 using equation (5.3), while UE2 using (4.5). Using MUST cat.2 with 0.3
, BER of UE1
is almost superior to UE2 when 0
b
E
N is larger than 2 dB, while in the case of 0.2
, to achieve
that, 0
b
E
N needs to be larger than 15 dB. The reason for this is MUST cat.2 ensures Gray-coded
mapping for composite constellations maximum a single-bit error for sufficient 0
b
E
N , if allocating
more power to UE1, we are “protecting” UE1 more than UE2. Compared to Figure 8, MUST
cat.2 is also better than MUST cat.1.
Figure 9. BER of two users in MIMO-NOMA using MUST cat.2 with different power allocation ratios
Figure 10 shows the results when the SISO channel has multiple taps, we need to scale the
analytical expression SNR, but due to error in limited ZF equalization causing ISI, simulations
barely fit derived BER formulas. When the system is combined with OFDM (see Table 2 for
parameters), BER curves match the expressions due to ISI elimination in cyclic prefixes. It is
noteworthy that SNR must be scaled for OFDM signals.
Table 2. Simulation parameters for two-tap fading channels
Parameter Value
UE1’s average channel gain
2
1 1
E 1
g
h
UE2’s average channel gain
2
2 2
E 0.5
g
h
Power allocation ratio 0.2
Single antenna transmission power 1
S
P
Number of FFT points 64
Number of data subcarriers 52
Number of zeros 1 DC, 11 guard bands
Number of cyclic prefixes 16
Channel information Perfectly known at receivers
Equalization method ZF
Fading channel Rayleigh SISO 2 taps
14. International Journal of Computer Networks & Communications (IJCNC) Vol.13, No.6, November 2021
106
Figure 10. BER of two NOMA users in SISO-ZF-OFDM and SISO-ZF systems using MUST cat.1
8. CONCLUSION AND FUTURE WORK
This research has introduced BER expressions for downlink MIMO-NOMA-ZF systems using a
SIC receiver, serving two users with QPSK modulation over an uncorrelated quasi-static
Rayleigh channel. Simulation results are perfectly matched with analytical expressions, not only
in different power allocation ratios but also MUST type 1 and 2 for signal generations. The
results show that MUST type 2 has better performance than type 1 due to Gray-mapping rules,
and when combined with OFDM, the system can minimize ISI, the simulations fit well with the
proposed theory. An approach to compare the performance between SISO and MIMO in the
NOMA system has also been clarified.
When the channel is bad or there is no need for high data rate, we can consider using diversity
instead, such as space-time coding, or develop a machine-learning detection system to ensure
integrity. Future work can be conducted for higher modulation orders, antenna beam forming,
optimal power allocation, MMSE or different equalization techniques, increasing the number of
users, having non-linear effects, and over correlated channel models.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
ACKNOWLEDGMENT
This research is funded by Vietnam National University HoChiMinh City (VNU-HCM) under
grant numberC2019-18-32.
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AUTHORS
Vu Tran Hoang Son received a B.S. degree in Electronics and Telecommunications,
minor in Telecommunications and Networks, from the University of Science, Vietnam
National University, HoChiMinh City (VNU-HCM). He is focusing on new-generation
mobile networks and wireless communications.
Dang Le Khoagraduated B.E. and Ph.D. in Radio Physics and Electronics from
University of Science, Vietnam National University, HoChiMinhCity (VNU-HCM). He
is the head of the Telecommunications and Networks Department, University of Science,
VNU-HCM. His current research interests are in the areas of wireless communications
and digital signal processing for telecommunication.